This is a Phase I study for treatment with I-131 Metaiodobenzylguanidine (MIBG) in patients with metastatic carcinoid. The primary objective of the study is to determine the maximum tolerated dose of I-131 MIBG in patients with untreated metastatic carcinoid. There is documentation in the literature that patients with metastatic carcinoid that uptake MIBG can obtain at least subjective improvement in their disease related symptomatology with treatment using I-131 MIBG. The maximum tolerated dose has not yet been determined and that is the goal of the current study. We hope that higher doses will improve response, both subjectively and objectively. The most recent cohort being treated is at 400 mCi of I-131 MIBG and the one patient in this cohort, at this time is eight weeks out, has shown both subjective and objective improvement without bone marrow toxicity. This is the third cohort with dose increases at 50 mCi per cohort. No dose limiting toxicities have been seen yet. Two more subjects are needed for the current cohort and we hope to continue enrolling patients to determine a maximum tolerated dose.